The Internal Revenue Service is warning consumers about nationwide telephone scams. Photo: Reuters

The IRS may really, really want you to pay the money you owe to the government. But there are some lines even the taxman won’t cross -- like calling to shake you down for cash and sounding pretty darn mad about the whole thing. Scammers, however, are a different story.

“These telephone scams are being seen in every part of the country, and we urge people not to be deceived by these threatening phone calls,” IRS Commissioner John Koskinen said in a statement. “We have formal processes in place for people with tax issues. The IRS respects taxpayer rights, and these angry, shakedown calls are not how we do business.”

How can you tell the difference between the fake IRS and the real IRS? Here are five things the agency says it will never, ever do:

1. Call you about taxes you owe without first mailing you an official notice.

2. Demand that you pay taxes without giving you the opportunity to question or appeal the amount they say you owe.